Author ORCID Identifier
Date Available
12-18-2025
Year of Publication
2023
Degree Name
Doctor of Philosophy (PhD)
Document Type
Doctoral Dissertation
College
Medicine
Department/School/Program
Molecular and Cellular Biochemistry
First Advisor
Dr. Matthew S. Gentry
Abstract
Glycogen is the primary glucose storage carbohydrate in mammals, and it is synthesized in most tissues. As glycogen architecture modulates its role in metabolism, it is essential to accurately evaluate and quantify glycogen, glycogen phosphate, and chain length of glucose monomers. Simultaneous quantitation of glycogen architecture is challenging. This work describes a highly-sensitive method for the detection of both glycogen-derived glucose and glucose-phosphate esters utilizing gas-chromatography coupled mass spectrometry (GCMS). We then integrated this glycogen quantitation workflow into a routinely utilized metabolomics-based assay. The work presented describes a workflow for the normalization of polar metabolites utilizing amino acids derived from the insoluble fraction that reduces biological variance and increases detection of small metabolite changes. We extended our mass spectrometry tool kit to include a method to define spatial glycogen architecture in mouse and human tissues using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Lastly, we demonstrate that glycogen stores and architecture are heterogeneous among the glycogen accumulating cancers, including the pediatric cancer, Ewing sarcoma. A clinical feature of Ewing sarcoma is the accumulation of Periodic acid-Schiff positive aggregates. Armed with these mass spectrometry techniques, we discovered profound intra-tumoral glycogen accumulation compared to adjacent stroma, normal, muscle, and necrotic tissue. This intra-tumoral glycogen also has an increased phosphate content and distinct chain length profile compared to normal glycogen found in adjacent and patient-matched tissue. Notably, genetic manipulation and pharmacological inhibition of glycogen synthesis, or removal of glycogen phosphates, halted Ewing sarcoma tumor growth in xenografted mouse models. Our work provides insights into glycogen accumulation and uncovers a new therapeutic target for Ewing sarcoma.
Digital Object Identifier (DOI)
https://doi.org/10.13023/etd.2023.027
Funding Information
This study was supported by the National Institute of Health (NIH) grants to M.S.G. R35 NS116824, P01 NS097197, NIH grant R01, and to L.E.A.Y. NIH/NCI F99CA264165. This research was also supported by funding from the University of Kentucky Markey Cancer Center and the NIH-funded Biospecimen Procurement & Translational Pathology Shared Resource Facility of the University of Kentucky Markey Cancer Center P30CA177558.
Recommended Citation
Young, Lyndsay E. A., "Advancements in glycogen detection and spatial profiling reveals a new therapeutic path for Ewing sarcoma: a non-traditional glycogen storage disease" (2023). Theses and Dissertations--Molecular and Cellular Biochemistry. 62.
https://uknowledge.uky.edu/biochem_etds/62
